need help with 60' times
 

i'm in need of some help with getting my car to 60 foot constantly on the stop. right now i leave at wide open throttle 6000 rpm(play back after every pass and it's at 6000) 6.5 psi in rear on hoosier. tires have about 30 passes use to run goodyears at the same. one pass it'll go 1.51 then the next run it'll go 1.60, then go 1.55. i've checked for coil bind, sticky calipers, line lock is releasing.

Re: need help with 60' times
 

Can you give us a little more info...
Whats your first number at
Whats your RPM on the stop
Whats your time on the stop
Approx Hp, and whats it run wide open

All could be helpfull in making a guess...plus do you have a data recorder or a playback tach ?

Re: need help with 60' times
 

first number is .200. second number is around 2.00 dependes on the weather. makes 650 hp at 6700 shift on rpm at 7000. weighes 2400 with me. goes 9o's at 1.26 in 60.

Re: need help with 60' times
 

forgot 4300 on the stop and have a playback tach

Re: need help with 60' times
 

Are 60' times constant with the stop off? If yes, then you need to see if it is maintaing a constant RPM while on the stop.
Since you are shifting on RPM it will increase RPM while on the Stop. It needs to increase the same amount all the time.
Shifting by time might solve the problem.

Re: need help with 60' times
 

I would look at two things..

First I'm assuming that you are running 10.90 (with 2 secs in the stop)..

I would try shifting on time, like at .3, and see if that makes it any better...if you play back the tach, are you gaining alot of RPM before the stop comes off ? If so this could make you're 60's inconsistant...if you cant shift on time try lowering your stop RPM to 3900-4000, this can help with the RPM gain...

Secondly, you may be spinnning at the hit, are your reaction times varying with the 60 ? If you are spinning lowering your starting line RPM , along with changing your first number to .05 can help....

Re: need help with 60' times
 

I think Dave may have hit on it with spinning on the hit.. 6.5 lbs at 2400 lbs sounds at bit low to me.. you might want to try bumping up to 7 or 7.5 before you start chasing ghosts.. if it gets better at 7, then try 7.5..

Re: need help with 60' times
 

He would want to lower his air? If he is spinning at 6.5 and you put more air he should spin more. We run 4.7 at day time and if track is good we run 5.0.

Re: need help with 60' times
 

This is a door car. I'm sorry we run a dragster. I was reading his post and he could be leaving way to high on rpm's try lowering to 4,000 to 5,000.

Re: need help with 60' times
 

I also think you should,

1. Leave at a lower rpm, at 6000, you should be holding a lot in the delay box, leaving at 4000-5000rpm would allow the hit to be more less agressive tightening up your 60ft ets and would just adjust the delay less. Lou is also right about the car being consistent out the door, if not theres your starting pt.and you should get that sorted before using a stop.

2. Does you pedal have a definitive stop on the firewall and does the firewall flex when you pound the pedal.

3. If you shift on time car will also get more consistent as Dave said but having the motor to pull you thru in 2nd gear is important as the convertor gets stressed coming off stop at say 4200 rpm .

4. I run 9 psi in my 16x33 tiresfor s/st, leave at 5200 1st # .05, shifting at .75 at 4100,4200 stop rpm weather dictating.

Re: need help with 60' times
 

What kind of stop do you have? On my car I was chasing inconsistent 60' times that would swing about as much as yours. I run an inline stop and it turned out the air cylinder was sticking when it would drop on the stop. So one time it would stick a little as it dropped and the 60 would be way fast, next time it wouldn't stick and it would be way slow.

Re: need help with 60' times
 

i'm running a inline stop to. how did you figure out that it was sticking. and what was the fix? thanks for the replys guys. was out this weekend trying the shift on time thing, no luck with that.

Re: need help with 60' times
 

Define "No Luck"

Re: need help with 60' times
 

Really. Show me a successful .90 racer who shifts on RPM... I don't know any.

Re: need help with 60' times
 

Come on now, Chris.. I shift on RPM and my car is very consistent to the 1000 ft.. it's from there to the stripe that I begin to think too much.. and the "GOTTA TAKE THE STRIPE" syndrome kicks in.. but maybe I'm just lucky...

Re: need help with 60' times
 

But I don't know you :)

Seriously, though, I know a half-dozen people who've tried it (including me), and the tradeoff in getting into the HP band isn't worth the randomness of the climbing of the RPMs when on the stop. Everyone I know is shifting earlier and earlier, we're down to 1.0 seconds, and I know a bunch of people who run in second the whole 1320.

Re: need help with 60' times
 

If you shift on time you may need to leave the rpm up around 4300. There was a good article on Biondo's site about setting up a stop.

Re: need help with 60' times
 

One thing I found was a break caliper sticking,thats one thing that took me a while to find. Make sure your car rolls easy,and free. Line locks and a sticky break caliper,will for a fact make 60's jump all over the place. Theres always 100's of reason,and it turns out to be ONE that someone on this site will have had. LOTS of good information on this sight and I thank you all for it. :)

Re: need help with 60' times
 

No one asked about 4 link? Ladder bar settings? Rigid wall tires versus soft? If the going up on air helps that would tell some info.